<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      //字符串trimStart、trimEnd清除字符串左右空白

      //数组方法flat将高阶数组转化为低阶数组
      const arr = [1, 2, 3, 4, [5, [6, 7, 8, 9]]]
      console.log(arr.flat(2))
      //symbol.prototype.description
      const str = Symbol('sam')
      console.log(str.description)
    </script>
  </body>
</html>
